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A hockey player hits a puck with her stick, giving the puck an initial speed of 4.40 m/s. If the puck slows uniformly and comes to rest in a distance of 22.0 m, what is the coefficient of kinetic friction between the ice and the puck?

Respuesta :

To solve this problem it is necessary to make a correlation between the energy lost by the frictional force and the kinetic energy by the puck.

Considering the definitions for the friction force as a product between the coefficient of friction and the normal force (mass by gravity) we have to:

[tex]W_f = KE[/tex]

[tex]F_f \Delta x = \frac{1}{2}mv^2[/tex]

[tex](\mu mg)\Delta x = \frac{1}{2} mv^2[/tex]

Where,

[tex]\Delta x[/tex] = Distance traveled

v = Velocity of the puck

m = mass of the puck

g = Gravitational acceleration

[tex]\mu =[/tex] Coefficient of kinetic friction

Re-arrange to find the Coefficient of kinetic friction

[tex](\mu mg)\Delta x = \frac{1}{2} mv^2[/tex]

[tex](\mu g)\Delta x = \frac{1}{2} v^2[/tex]

[tex]\mu = \frac{1}{2} \frac{v^2}{g\Delta x}[/tex]

Replacing we have finally,

[tex]\mu = \frac{1}{2} \frac{4.4^2}{(9.8)(22)}[/tex]

[tex]\mu = 0.0448[/tex]

Therefore the coefficient of kinetic friction between the ice and the puck is 0.0448